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