It is shown that any n-chromatic graph is a full subdirect product of copies of the complete graphs K n and K n+ 1, except for some easily described graphs which are full subdirect products of copies of K n+ 1-{°-°} and K n+ 2-{°-°}; full means here that the projections of the decomposition are epimorphic in edges. This improves some results of Sabidussi. Subdirect powers of K n or K n+ 1-{°-°} are also characterized, and the subdirectly irreducibles of the quasivariety of n-colorable graphs with respect to full and ordinary decompositions are