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