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