Unlocking colors in Super Street Fighter 4 is a bit different than it was in the previous version. You don’t unlock colors for all characters at once like in Street Fighter 4, you just unlock them for each character by playing with that specific character a certain number of times.
All you have to do to unlock all of the colors for any character is to play 16 matches. You’ll unlock a color every other match you play. The nice thing though is that you don’t have to completely finish any of the matches, all you have to do is start one, then quit.
The easiest way to do it is to go into Versus mode and select Player vs. CPU. Pick the character you want to unlock colors for, and once the match starts press start and select Character Change, and do this until you’ve unlocked all of the colors you want.
Note that while you’re at it, you’ll also be unlocking the characters taunts as well.