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