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