Well, at the top right hand side it says Iris, so I guess it must be Iris, with a rainbow behind her.
In Greek mythology, Iris is the personification of the rainbow and messenger of the gods. As the sun unites Earth and heaven, Iris links the gods to humanity. She travels with the speed of wind from one end of the world to the other, and into the depths of the sea and the underworld. (Wiki)
http://en.wikipedia.org/wiki/Iris_%28mythology%29