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