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