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