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