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