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