yes they do.
when basking they will become as dark as they can to absorb the most heat and rays.
when they are done 'charging' they turn a really bright color.
usually their colors become dull when they get cold and you should plug them in - er, i mean put them back under their lights.
their beards also change colors (usually to black, not sure what the red bearded ones look like when the '
black beard').
the way their beards change also tells you their mood.
this is Mr Dargon's system:
-full yellow - happy
-full black- angry
-half black - sad
-all black and BRIGHT orange everywhere else - horny
every beardie is different and you will get to know what each shade means for that particular beardie.