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