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