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