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