The fall leaves of sweetgum trees vary in color from purple to orange to yellow to red. Sweetgum trees have pointy, star-shaped leaves. Also pointy are the gumballs borne by most varieties, but most people consider these seed pods to be a nuisance to clean up after. I recommend the fruitless 'Rotundiloba' sweetgum tree, instead, so that the "messy trees" label won't make you steer clear of sweetgum trees and lose out on enjoying their attractive fall leaves.
If you can't find a variety that doesn't drop gumballs, you could still plant a sweetgum tree in an area where you won't have to bother cleaning up the gumballs (such a space may, of course, be lacking in small yards), but where you can still admire the brilliance of its fall leaves.