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