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