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