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