It would be impossible to list all the colours of a dragon, for they are as many and varied as the dragons themselves. There are the blue dragons, whose colour ranges from dark blue to silver, the red dragons, dragons of every imaginable shade of green, the blacks, whites, browns and of course the legendary golden dragons, whose scales glisten in tones of pure gold. 
Most dragons however are not limited to one shade, more likely you will find that their colour is made up of several different hues of one main colour blending together with a metalic lustre.