NASA DAWN Image: The large asteroid Vesta

The large asteroid Vesta appears multihued in this image, which uses the filters on the Dawn spacecraft to greatly enhance the subtle color differences on the surface. 

Each is probably due to different chemical compositions of the surface material. Up close, Vesta would look pretty much grey to the eye; see the text below for an explanation. 

Photo by NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI