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