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