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