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