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