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