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