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