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