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