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