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