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