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