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