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