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