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