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