One vertex per element, one color per generator, with an edge from x to x·s.
(2,3)(5,6)(7,10)(8,12)(9,11)(13,14)(15,21)(16,19)(17,20)(18,22)(23,26)(24,28)(25,27) involution — undirected(1,2,4,3)(5,7,9,12)(6,10,11,8)(13,15)(14,18)(16,22)(17,23)(19,21)(20,28)(24,25)(26,27)(5,8,9,10)(6,7,11,12)(14,19)(15,22)(20,27)(23,24)(6,11)(7,12)(14,19)(15,23)(17,25)(18,26)(21,28)(22,24) involution — undirected(1,3,4,2)(14,19)(18,21)(20,27)(26,28)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.