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