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