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