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