Welcome to TFF. You’ve got a good sized tank there and lots of room for more fish. We’d love to see a picture of what you’ve got in there so far.
What a good sized tank. You have a lot of colorful choices for fish, depending on your goals.
Have you kept fish before?
If you’re interested in a general community tank, people often look for fish that hang out at the bottom, other fish that hang out on the substrate, and other fish that swim around mid-tank. Then you usually have something interesting to look at somewhere in your tank at all times.
I like the South American cichlids so one of my favorite colorful fish is the Blue Acara or the Electric Blue Acara. The German blue ram is also a pretty fish and you might also consider the apistogramma (dwarf cichlids).
There are some very colorful killifish which might interest you, like the Clown Killi or a Bluefin Notho.
I am probably like most others on this board as I always get a little excited when someone posts about their new tank and have yet to stock it. We look forward to seeing how your tank evolves.