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