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