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