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