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