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