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