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