Last semester I taught a public speaking class which was mostly made up of adults, specifically women, many of whom had very good jobs and were quite accomplished. The few males in the class were also very accomplished. This group loved food! They found a way to bring food into just about every class. You should have seen our last class--a buffet of foods from all different cultures represented in the class: everything from Portuguese to Indian to Latino dishes, you name it, it was there.
One student, Laura, loved to bake and on no less than three occasions she brought these food color cakes. They were absolutely delicious, and even though I don't usually have sweets, I did try them. (OK, I did more than try one. She gave me one to take home and it lasted 2 days. I rationalized that I was going to give it to my neighbor, but that didn't happen.) There were all different colors. On one student's birthday, she brought a cake made up of the this student's favorite colors (I know, isn't she a sweetie?). It was purple and blue, and even though that sounds a little strange, it was beautiful.
So yes, this can be a versatile way of expressing a holiday or even just honoring someone who has birthday, retirement, etc., with their favorite colors.
However, being a more natural foods type of person, there's something a little weird about having something that's not a natural color! I guess, though, that as long as it's not red dye #4, there's nothing wrong with it, though, right?
Cher