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