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