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