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