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