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