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