A new set of color guides have started going up here on EventHubs.com. Huge props go to SFilp for helping put these together.This time around, the image quality is much improved from the original set of color guides that went up with vanilla Street Fighter 4.
In the future, all 35 characters will have sections like these posted, pretty close to the same order that the alternative costume packs are being released in.
If you find unlocking various colors fairly tedious, read over this guide on how to do it a bit faster.
I love color guides. Highlightable text with just one picture field would be more awesome, though.