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