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