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