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