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