GCC has an option now to color some of the output (http://gcc.gnu.org/onlinedocs/gcc/Language-Independent-Options.html)
Using ccache, it seems the color information is lost. It would be nice to handle this in the cache as it makes diagnostic much much faster.
Fixed in d875edef19d0ab157b2f6408330bb1392fd38f60 on the master branch.
Included in v3.2.