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