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