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