We report neutron-diffraction results on single-crystal CaMn2P2 containing corrugated Mn honeycomb layers and determine its ground-state magnetic structure. The diffraction patterns consist of prominent (1/6, 1/6, L) reciprocal lattice unit (r.l.u.; L = integer) magnetic Bragg reflections, whose temperature-dependent intensities are consistent with a first-order antiferromagnetic phase transition at the Néel temperature TN = 70(1) K. Our analysis of the diffraction patterns reveals an in-plane 6 × 6 magnetic unit cell with ordered spins that in the principal-axis directions rotate by 60-degree steps between nearest neighbors on each sublattice that forms the honeycomb structure, consistent with the PAc magnetic space group. We find that a few other magnetic subgroup symmetries (PA2/c, PC2/m, PS¯1, PC2, PCm, PS1) of the paramagnetic P¯3m11′ crystal symmetry are consistent with the observed diffraction pattern. We relate our findings to frustrated J1-J2-J3 Heisenberg honeycomb antiferromagnets with single-ion anisotropy and the emergence of Potts nematicity.