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