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