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