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