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