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