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