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