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