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