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)(11,15)(12,16)(13,14)(17,18)(19,23)(20,22)(21,24)(25,26)(27,31)(28,35)(29,30)(32,37)(33,40)(34,38)(36,39)(1,2)(3,5)(4,7)(6,8)(9,11,13,16)(10,12,14,15)(17,18,20,22)(19,23,24,21)(26,30)(31,38)(32,35)(39,40)(2,3)(6,7)(10,14)(12,15)(17,18,20,22)(19,21,24,23)(25,27,29,34)(26,31,30,38)(28,36,37,33)(32,40,35,39)(1,3,5,2)(4,7,8,6)(9,12)(10,11)(13,15)(14,16)(17,18)(19,21)(20,22)(23,24)(25,28)(26,32)(27,33)(29,37)(30,35)(31,39)(34,36)(38,40)(1,4,5,8)(2,6,3,7)(9,11)(10,12)(13,16)(14,15)(17,19,20,24)(18,21,22,23)(25,26)(27,31)(28,32)(29,30)(33,39)(34,38)(35,37)(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.