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