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)(25,26,31,36)(27,37,39,32)(28,35,30,33)(29,34,38,40)(1,3,4,7)(2,5,6,8)(9,10,14,11)(12,17,20,15)(13,18,21,16)(19,22,24,23)(25,26)(27,37)(28,33)(29,40)(30,35)(31,36)(32,39)(34,38)(1,2)(3,5)(4,6)(7,8)(10,11)(15,17)(16,18)(22,23)(25,27,31,39)(26,32,36,37)(28,38,30,29)(33,40,35,34)(9,11,14,10)(12,15,20,17)(13,18,21,16)(19,22,24,23)(25,28,31,30)(26,33,36,35)(27,38,39,29)(32,40,37,34)(1,3)(2,5)(4,7)(6,8)(9,12,14,20)(10,15,11,17)(13,19,21,24)(16,22,18,23)(25,29)(26,34)(27,28)(30,39)(31,38)(32,33)(35,37)(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)(25,30,31,28)(26,35,36,33)(27,29,39,38)(32,34,37,40)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.