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