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