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