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