We derive the multiparticle-correlation expansion of the excess entropy of classical particles in the canonical ensemble using a new approach that elucidates the rationale behind each term in the expansion. This formula provides the theoretical framework for an entropy-based ordering criterion that has been already tested for a variety of model fluids and thermodynamic phenomena. In view of future investigations of the phase diagram of colloidal mixtures, we detail in this paper the case of a two-component system of spherical and rod-like particles and discuss the symmetries underlying both the self and distinct pair-distribution functions under various geometrical constraints.