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