That sucks. I've had a pink lemonade cake, but the tartness of it seemed off to me.

If food coloring is your only problem, I wouldn't worry too much about it. Taste is more important than looks.
Especially if you're going to ice it anyway once it's baked (assuming you don't need food coloring for the icing).
No one will care, I promise.

I've muffed cakes when it came to icing them. I always make Mexican 3 milks cake and you have to pour a rather large amount of a milk mixture onto the cake (after poking lots of holes in it with a fork) and let it "soak" in the fridge for awhile. It makes the cake very soft and spongy, so icing it is hard to do. Especially since it's -impossible- to find Mexican-style non-dairy whipped topping like the stores in Phoenix use around here in TN. Something about the texture of it and whatnot is way different than Cool Whip or making it yourself (which I've tried)

EDIT:

Welp. Looks like food coloring wasn't your only problem. heh. Sorry.

maybe try rotating it and putting it back in the oven?