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