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