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