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