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