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