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