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