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