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