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