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