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