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