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