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