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