Very much depends on the Shepard. My "canon" main FemShep wears variations on the red/black/white Alliance/N7 color scheme, because she's still loyal to them, but my more renegade ManShep changed to Cerberus gold/gray/black (and all the squad members use their alternate looks in that playthrough, because then they all match). Other than that, though, I play around and change colors fairly often.
My rather mean current FemShep wears purple and green so she looks like Agent South Dakota from Red vs. Blue... I thought it was appropriate for a strongly renegade and hate-everyone-else kind of character.