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