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