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