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