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)(13,14)(15,24)(16,21)(17,27)(18,23)(19,22)(20,26)(25,28)(2,3)(15,25)(16,26)(17,19)(20,21)(22,27)(24,28) involution — undirected(1,2,4,3)(6,9)(10,12)(13,15,18,26)(14,20,23,24)(16,17,25,19)(21,22,28,27)(1,3,4,2)(13,16)(14,21)(15,17)(18,25)(19,26)(20,22)(23,28)(24,27)(5,7,8,11)(6,10,9,12)(13,17,18,19)(14,22,23,27)(15,25,26,16)(20,28,24,21)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.