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