Your True Colors ARE Beautiful!
I came across a similar art idea on Pinterest from http://elementaryartfun.blogspot.com/2011/09/fun-with-photoshop.html. She used the computer to edit a picture of a little girl painting the sky. I thought it would be easier to have students use watercolors to paint their rainbows.
A colleague and I took pictures of students pretending to paint areas all around the playground during recess. Students turned their back to me while holding a paint can in one hand and a paint brush in the other. We decided to put it together with Cindy Lauper's "True Colors." We read the book "Have You Filled a Bucket" and talked with students about how we can make a better world. To accompany their art, students wrote about ways to make the world a more beautiful place. They came up with ideas like giving hugs, picking up trash, sharing with friends, etc. It was a great lesson in friendship! I had more comments on this art display than any other I had ever done. Thanks for the art idea Natalie! The students loved it! It also went well with our weather unit! If anyone else does something similar, please leave me a comment letting me know what you have done. I am always open to new ideas!