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