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