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