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