We construct a supersymmetry algebra which satisfies the triality rules governing the multiplication of « coloured » quark variables. Quarks and leptons are treated on an equal footing. The affine structure imposed on the unified space of Fermionic and Minkowski co-ordinates forces the introduction of separate leptonic and hadronic (quark) variables. Some basic properties of dynamical superstructures based on the coloured superspace are discussed. It is pointed out, in particular, that supersymmetric theories based on coloured superspace allow for an interpretation of superfield components in terms of lepton and quark fields; the theory permits separate conservation of lepton and baryon numbers.