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