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