Charmed baryon decay plays an important role in studying the weak and strong interactions. Topological diagram is an intuitive tool for analyzing the dynamics of heavy hadron decays. In this work, we investigate the topological diagrams of charmed baryon antitriplet (Bc3¯) decays into a light baryon octet (B8) and a light meson (M). A one-to-one mapping between the topological diagram and the invariant tensor is established. The topological diagrams of the Bc3¯→B8SM modes (where B8S and B8A are the q1↔q2 symmetric and antisymmetric octets) and the diagrams with a quark loop are presented for the first time. The completeness of topologies is confirmed by permutation. The linear relations of topologies are obtained by deriving the relation between the topological amplitudes constructed by the third- and second-rank octet tensors. It is found the topologies contributing to the Bc3¯→B8SM modes can be determined by the topologies contributing to the Bc3¯→B8AM modes, and vice versa. The equations of SU(3) irreducible amplitudes decomposed by topologies are derived through two different intermediate amplitudes. However, the inverse solution does not exist since the number of topologies exceeds number of SU(3) irreducible amplitudes. Applying this framework to the Standard Model, it is found there are thirteen independent SU(3) irreducible amplitudes contributing to the Bc3¯→B8M decays. Among these, four amplitudes associated with three-dimensional operators are significant for CP asymmetries. Considering the suppressions due to small Cabibbo-Kobayashi-Maskawa matrix elements and the Körner-Pati-Woo theorem, the branching fractions of charmed baryon decays are dominated by five SU(3) irreducible amplitudes in the SU(3)F limit. Quark-loop diagrams could enhance the U-spin breaking effects and increase the branching fraction difference of two decay channels. Systematic measurements of branching fractions of the singly Cabibbo-suppressed modes could help identify promising channels for searching for CP asymmetries in the charmed baryon sector. Published by the American Physical Society 2024