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