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