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