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