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