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