i will caution - be careful and make sure to taste test as you add coloring, it can change the flavor if you use too much.
here is an example of cupcakes i made with purple frosting to celebrate mardi gras...to get the swirl effect put a different color on each side of a piping bag (i suggest sticking with only 2 colors) then pipe using a swirl motion.
They don't always have to match perfectly, go with the flow
here is some color inspiration
for the girly girl...
something as simple as color makes these cupcakes really pop!