At first I thought that, if going to such saturated color in this picture, it might be better to make the color appear more obviously arbitrary. But then I found I liked much of its structure and was mainly bothered by the way the yellow-green seemed to form a separate block. Using the Color Balance panel in CS4, on the third try, I moved the three sliders 18 clicks to the right for the Shadows and Midtones and 18 clicks to the left for the Highlights, without preserving luminosity. The attached is otherwise the same as your original.
Bruce