  We propose a modification of standard QCD description of the colour triplet
of quarks describing quark fields endowed with colour degree of freedom by
introducing a 12-component colour generalization of Dirac spinor, with built-in
Z_3 grading playing an important algebraic role in quark confinement. In
"colour Dirac equations" the SU(3) colour symmetry is entangled with the
Z_3-graded generalization of Lorentz symmetry, containing three 6-parameter
sectors related by Z_3 maps. The generalized Lorentz covariance requires
simultaneous presence of 24 colour Dirac multiplets, which lead to the
description of all internal symmetries of quarks: besides SU(3) \times SU(2)
\times U(1), the flavour symmetries and three quark families.
