One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,6)(4,5)(7,8)(9,10)(11,13)(12,14)(15,16)(17,18)(19,24)(20,22)(21,23)(25,26,29,32,28,31,36,39)(27,33,35,40,34,30,37,38)(2,5)(6,8)(9,11,12,15)(10,13,14,16)(17,19,21,20)(18,22,23,24)(25,27)(26,30)(28,34)(29,35)(31,33)(32,38)(36,37)(39,40)(1,3)(2,6)(4,7)(5,8)(10,14)(13,16)(18,23)(19,20) involution — undirected(3,7)(6,8)(17,20,21,19)(18,22,23,24)(27,34)(30,33)(35,37)(38,40)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.