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