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