I just did a job refurbing the inside of a walk-in cooler with diamond plate. Didn't have much to cut as it worked out to almost full sheets everywhere. For the cuts that I did make I used a jig saw with a fine metal blade, and a straight edge guide. I had to file a few edges here and there to get rid of the rough stuff, but you'll probably have that with any cutting tool (except maybe a laser).
As noted, where hearing protection. And definitely eye protection, no matter how you decide to cut it.
Depending on the type of cut you want to make and how much cutting you have to do, there are various methods you can employ.
For small cuts I would just use a hacksaw with a fine tooth blade.
It can be cut on a table saw or with a circular saw with a good carbide tipped blade (the more teeth the better), or better yet, one like Mike linked to that is designed for non-ferrous metals. The fiber blades designed for ferrous metals don't work as well because the aluminum is too soft, and it will tend to clog the fibers.
You can also cut it on a band saw. You'll get better results with a larger blade, the right number of teeth-per-inch, and a slower speed. The thinner the plate the more teeth-per-inch you want. If it's 1/4" plate I would want about 14-18 tpi. For 1/8" I would want 18-24 tpi. But if you get too many tpi the cut will be slower and the blade will tend to clog.
The aluminum won't throw a shower of sparks like steel will, but the spray will still be hot. I would do the operation away from sawdust and other flammables, or disengage your table saw or band saw from your dust collection system before cutting it. This is one of those cases where you REALLY NEED TO LET THE TOOL DO THE WORK and you only act as a guide. Trying to force it to speed things up is going to create a lot of excess heat and wear out your blade almost immediately.
The blade that Mike linked to is the bet bet. But if you don't want to wait to get one in from Amazon, a good carbide toothed blade in a circular saw works well. I had to rip some pieces of 1/4" plate to finish up a shop that I built and this combination along with a good guide for the saw worked great. Wear eye and ear protection as well as good gloves because the housing around the blade gets hot. A little lube on the blade wouldn't hurt either.
If its 1/4" thick or less, you can cut it with a carbide tipped blade. One with negative rake or minimum positive is better than something like the craftsmen Dyanite blades (teeth come to a forward facing point) I have had a dyanite style throw carbide teeth at me. As already stated, the more teeth the better (ie 40 or more for a 10" blade, with 60 a good number.) The preferred would be the one Mike linked to.
It is much better to use a table saw than a circular saw or miter saw. The latter two have the teeth coming up and will shower you with hot metal chips. Regardless, wear good eye protection with goggle type protection to cover sides and tops.
On the table saw, this is a case where raising the blade full up is better, so you get a downward chopping action. If you have the blade set low like cutting ply, etc, (1/2 tooth above the top is recommended by some), you will build up enough friction through the longer cut to melt the aluminum, and it will gall on the blade, greatly upping the heat and ruining your blade (quicker). This is another reason not to use a miter saw. You will want to clean out the saw under the insert after you are done, and you do not want to use a ZCI (metal will build up on the edge). Use the stock insert if you have one.
I have used standard kerf blades for this but never have tried thin kerf, so don't know how well that will work.
A bandsaw with the right teeth and speed will work, but works better if you can keep the blade lubed. (messy). IF the blade starts galling, stop until it cools.
You will also want ear protection, and wear a long sleeved shirt (cuffs buttoned).
I've had great luck cutting aluminum on the table saw with a Craftsman blade meant for aluminum. Just BE CAREFUL with kick back. I had a small piece of 1/4" kick back on me. Luckily I moved fast enough to let it only slice my shirt open and hit my steel entry door 10' behind me - it dented the door pretty well.
I've cut aluminum before with a circular saw & carbide blade. All these guys are right. Use eye/hearing protection. A full face shield will help. If you are making a straight cut, a rip guide is a must as you then are able to focus more on feed speed and less on keeping the cut straight. About the blade depth, I'd keep it at about 1/2 blade depth. If it's too shallow you will get heat buildup, melting, and galling. Too deep makes it easy to chip off a tooth in an aggressive cut. Be slow with your feed rate & don't force the blade too much & if you can, cut from the backside unless using a TS or BS. A little oil on the blade & cut wouldn't hurt. The suggestion about the long sleeved shirt is a must - just be sure it isn't flannel or a knit shirt. Aluminum filings tend to stick to those & end up in the laundry & it'll make your laundry fairy turn into a gremlin!