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