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