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