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)(11,12)(13,21)(14,15)(16,18)(17,23)(19,22)(20,24)(25,26,31,35)(27,32,36,40)(28,33,37,38)(29,30,34,39)(3,7)(5,8)(10,15)(12,16)(17,21)(20,22)(25,27,31,36)(26,32,35,40)(28,29,37,34)(30,38,39,33)(1,2)(3,5)(4,6)(7,8)(10,15)(11,18)(17,21)(19,24)(27,36)(28,37)(32,40)(33,38) involution — undirected(9,11,14,18)(10,16,15,12)(13,19,23,24)(17,22,21,20)(25,28)(26,33)(27,29)(30,32)(31,37)(34,36)(35,38)(39,40)(1,3)(2,5)(4,7)(6,8)(9,12,14,16)(10,11,15,18)(13,22,23,20)(17,24,21,19)(25,29)(26,30)(27,37)(28,36)(31,34)(32,38)(33,40)(35,39)(1,2)(3,5)(4,6)(7,8)(9,13,14,23)(10,17,15,21)(11,19,18,24)(12,20,16,22)(25,30)(26,34)(27,38)(28,32)(29,35)(31,39)(33,36)(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.