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