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