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