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