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