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