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