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