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