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