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