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