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