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