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