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