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