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