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