Automorphisms of Coxeter groups of rank three

If $W$ is an infinite rank $3$ Coxeter group, whose Coxeter diagram has no infinite bonds, then the automorphism group of $W$ is generated by the inner automorphisms and any automorphisms induced from automorphisms of the Coxeter diagram. Indeed $\operatorname{Aut}(W)$is the semi-direct product of $\operatorname{Inn}(W)$ and the group of graph automorphisms.