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