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