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