Can you use food coloring to paint on your cake or you need to use something else to paint on the cake?
Do you mean to paint on the icing or on the cake itself. If you want the cake itself to be colored you can buy flavored cake mixes like Strawbery that are pink.
I used to do this when my kids were small. I got the recipe and idea from a friend who did cakes. White frosting. Your cake is your canvas. My kids even got to paint. Used new water color brushes, I cut them off blunt so they could be more professional. I even have powdered colors that could be mixed, but the regular food color colors were the best.
After frosting and before painting, freeze the cake for about 1 hr to help set it up. I have a frosting recipe, she did not use ordinary bought frosting. Contact me for the recipe.