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