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