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