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