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