  In a recent paper, Barot and Marsh presented an explicit construction of
presentation of a finite Weyl group by any seed of corresponding cluster
algebra, i.e. by any diagram mutation-equivalent to an orientation of a Dynkin
diagram with given Weyl group. Extending their construction to the affine case,
we obtain presentations for all affine Coxeter groups. Furthermore, we
generalize the construction to the settings of diagrams arising from
unpunctured triangulated surfaces and orbifolds, which leads to presentations
of corresponding groups as quotients of numerous distinct Coxeter groups.
