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)(25,26,31,34)(27,32,37,40)(28,29,30,33)(35,36,38,39)(2,5)(6,8)(10,12)(11,18)(16,20)(19,21)(25,27,31,37)(26,32,34,40)(28,38,30,35)(29,39,33,36)(1,2,4,5)(3,6,7,8)(10,12)(15,17)(16,20)(23,24)(25,28,31,30)(26,33,34,29)(27,35,37,38)(32,39,40,36)(3,7)(6,8)(9,11,14,18)(10,15,12,17)(13,21,22,19)(16,24,20,23)(25,27)(26,32)(28,35)(29,36)(30,38)(31,37)(33,39)(34,40)(1,2)(3,6)(4,5)(7,8)(9,12,14,10)(11,17,18,15)(13,20,22,16)(19,24,21,23)(25,29,31,33)(26,28,34,30)(27,36,37,39)(32,35,40,38)(1,3)(2,6)(4,7)(5,8)(9,13,14,22)(10,16,12,20)(11,19,18,21)(15,23,17,24)(25,30,31,28)(26,33,34,29)(27,35,37,38)(32,36,40,39)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.