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