We construct the E8 algebra in terms of the tensorial representations of its SU9 maximal subalgebra. We then construct the supersymmetric gauge-invariant boson-fermion coupling, and decompose it completely into terms exhibiting color SU3 and family SU5 symmetries. This work promotes a scheme of E8 super grand unification that is based on a perfect symmetry between particles and antiparticles, rather than a symmetry between quark-lepton generations and their enigmatic mirror conjugates. Whereas the emergence of a definite chirality for low-energy weak interactions still depends on the yet unresolved problem of symmetry breaking, a picture of weak decays emerges, in which multiple W vector bosons, rather than a single one, are the fundamental weak mediators between multiple charged leptons and associated multiple neutrinos, or between multiple upquarks and their associated multiple downquarks.