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