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