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