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