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