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