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