Say you have three clauses: "x OR y", "NOT x OR z", "NOT y OR NOT z". Let me build the graph step by step. Clause adds edges: NOT x → y and NOT y → x. Clause adds: x → z and NOT z → NOT x. Clause adds: y → NOT z and z → NOT y. That is your implication graph. It has nodes (x, NOT x, y, NOT y, z, NOT z) and edges total.
Now you run SCC on this graph to check satisfiability. The SCC structure will tell you if this formula has a solution.