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)(15,20)(16,17)(18,19)(21,22,25,26)(23,27,28,24)(1,2,4,3)(5,6,8,10)(7,9,12,11)(14,19)(15,17)(21,23,25,28)(22,24,26,27)(1,3,4,2)(13,15,18,17)(14,20,19,16)(21,22)(23,24)(25,26)(27,28)(5,7)(6,9)(8,12)(10,11)(13,16)(14,15)(17,19)(18,20)(21,23)(22,24)(25,28)(26,27) involution — undirected(5,6)(7,9)(8,10)(11,12)(13,17,18,15)(14,16,19,20)(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.