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