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