One vertex per element, one color per generator, with an edge from x to x·s.
(2,4)(6,9)(7,11)(10,12)(13,14)(15,18)(16,19)(17,21)(20,24)(22,25)(23,26)(27,28) involution — undirected(5,6,7,9,8,10,11,12)(13,15)(14,18)(16,23)(17,22)(19,26)(20,27)(21,25)(24,28)(1,2,3,4)(6,10)(9,12)(15,22)(18,25)(23,28)(26,27)(14,19)(16,24)(18,26)(20,21)(23,28)(25,27) involution — undirectedA 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.