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