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)(12,15)(13,14)(17,18,21,20)(19,23,24,22)(26,30)(28,36)(31,34)(35,39)(2,4)(3,8)(9,11,14,12)(10,15,13,16)(18,20)(19,24)(26,30)(27,33)(32,37)(35,39)(3,8)(6,7)(11,12)(15,16)(17,18,21,20)(19,23,24,22)(25,26)(27,34)(28,32)(29,30)(31,33)(35,40)(36,37)(38,39)(1,3,5,8)(2,6,4,7)(9,12,14,11)(10,15,13,16)(17,19,21,24)(18,22,20,23)(25,27)(26,31)(28,35)(29,33)(30,34)(32,38)(36,39)(37,40)(1,4,5,2)(3,7,8,6)(9,13,14,10)(11,15,12,16)(17,20,21,18)(19,23,24,22)(25,28)(26,32)(27,35)(29,36)(30,37)(31,38)(33,39)(34,40)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.