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