Hallucinations remain challenging for large language models (LLMs), especially in factual generation. Existing mitigation methods often rely on retrieval, supervision, representation editing, or output-level decoding, while paying limited attention to how factual support is internally coordinated across attention heads. In this work, we study factual decoding from a head-level coordination perspective and find that unreliable generations are often associated with fragmented and unstable use of factual anchors across heads. To improve such coordination, we propose Head Coordination Graphs (HCG), a plug-and-play inference-time framework that models attention heads as interacting nodes. HCG uses explicit factual anchors as observable support signals to construct sparse head graphs and applies risk-gated propagation to adaptively regulate cross-head influence without parameter updates, additional training, or external knowledge. Experiments across multiple factuality and hallucination benchmarks demonstrate broad improvements in factual consistency across open-source LLMs, while analyses and ablations demonstrate the importance of head-level coordination, sparse graph construction, and risk-gated propagation.