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)(27,34)(31,39)(35,40)(36,38)(1,3)(2,5)(4,8)(6,7)(9,11,14,15)(10,16,19,24)(12,20,13,21)(17,23,18,22)(25,26,29,33)(27,35,34,40)(28,32,30,37)(31,38,39,36)(9,12,14,13)(10,17,19,18)(11,20,15,21)(16,23,24,22)(25,27)(26,31)(28,36)(29,34)(30,38)(32,40)(33,39)(35,37)(2,6)(3,8)(9,13,14,12)(10,18,19,17)(11,21,15,20)(16,22,24,23)(25,28,29,30)(26,32,33,37)(27,36,34,38)(31,40,39,35)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.