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