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