I have been asked to do a cake where the actual cake part is vanilla cake colored and poured in a pan to make a rainbow. Does anyone know where I could find a tutorial on how to do this?

Part of me thinks I could just pour different layers of colors into the pan, but then I see them where they are swirled or curved where each color comes almost to the top of the cake and I wonder if the colors would bleed into each other etc.

Any help would be much appreciated!!

Here's a few:
http://www.colourlovers.com/craft/blog/2009/03/05/how-to-make-a-rainbow-cake

http://www.cakecentral.com/modules.php?name=Forums&file=viewtopic&t=585413&highlight=rainbow

This one is for cupcakes, but I love her idea of using disposable cups and forks: http://www.youtube.com/watch?v=zKvSvvOwbTQ&feature=related

I did this recently and it worked out great.
Just put the white batter in seperate bowls, stir in the colors you want. Then one at a time, starting in the middle of the cake pan, pour the first colored batter. Pour the 2nd color in the center, right on top of the first color and it will spread. Pour the 3rd color directly on top of the 2nd color, etc, etc.

I used Americolors and it the colors were nice and vibrant when it baked.

Good luck!
KimAZ