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)(15,24)(16,26)(17,18)(21,22)(23,27) involution — undirected(1,2)(3,4)(5,7,9,8)(6,10,11,12)(13,14,19,23)(15,25,26,28)(16,22,24,21)(17,27,18,20)(2,4)(5,8,9,7)(6,10,11,12)(13,15,17,24,19,26,18,16)(14,21,20,25,23,22,27,28)(13,16,18,26,19,24,17,15)(14,22,20,28,23,21,27,25)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.