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