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