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)(15,19)(16,24)(17,21)(18,23)(20,25)(22,26)(27,28)(1,3,4,2)(5,6,8,10)(7,9,12,11)(5,6)(7,9)(8,10)(11,12)(13,15)(14,18)(16,22)(17,23)(19,21)(20,26)(24,27)(25,28) involution — undirected(5,7,8,12)(6,9,10,11)(13,15)(14,19)(16,22)(17,23)(18,21)(20,27)(24,26)(25,28)(13,14)(15,18)(16,20)(17,21)(19,23)(22,26)(24,25)(27,28) involution — undirected(13,16,17,25)(14,20,21,24)(15,22,23,28)(18,26,19,27)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.