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