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