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