With colors that would make Faberge green with envy, the Cartwheel galaxy stands out against a backdrop of other brightly-colored galactic bodies. The Easter egg appearance of this galaxy is due to false colors representing various wavelengths of light ultraviolet in blue, B-band visible light in green, infrared in red and x-ray radiation in purple.
The 'rings' of this galaxy are the aftermath of a collision between the Cartwheel galaxy and another galaxy about 100 million years ago. The first ripple is the blue outer ring, while the yellow-orange "yolk" of the Easter egg is a combination of visible and infrared light from the second ripple.

Source: Live Science