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