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