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