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