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