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