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