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