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