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)(16,21)(17,22)(18,23)(19,25)(24,28)(26,27) involution — undirected(1,2,4,3)(6,9)(10,12)(15,24)(16,18)(19,27)(20,28)(21,23)(25,26)(1,3,4,2)(5,7,8,11)(6,10,9,12)(13,15)(14,19)(16,24)(17,25)(18,26)(20,22)(21,27)(23,28)(13,15)(14,20)(16,24)(17,25)(18,26)(19,22)(21,28)(23,27) involution — undirected(13,16,17,18)(14,21,22,23)(15,24,25,26)(19,27,20,28)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.