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