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