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