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