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