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)(11,14)(12,17)(13,16)(15,20)(18,21)(19,23)(22,24)(25,26,29,32)(27,30,33,36)(28,31,35,38)(34,37,39,40)(1,3)(2,6)(4,7)(5,8)(10,11)(15,17)(16,18)(22,23)(27,33)(30,36)(34,39)(37,40) involution — undirected(9,10,14,11)(12,15,20,17)(13,16,21,18)(19,22,24,23)(25,26)(27,30)(28,31)(29,32)(33,36)(34,37)(35,38)(39,40)(2,7)(3,8)(9,11,14,10)(12,17,20,15)(13,18,21,16)(19,23,24,22)(25,27,29,33)(26,30,32,36)(28,34,35,39)(31,37,38,40)(1,4,5,6)(2,3,7,8)(9,12,14,20)(10,15,11,17)(13,19,21,24)(16,22,18,23)(25,26)(27,30)(28,31)(29,32)(33,36)(34,37)(35,38)(39,40)(1,3)(2,4)(5,8)(6,7)(9,13,14,21)(10,16,11,18)(12,19,20,24)(15,22,17,23)(25,28,29,35)(26,31,32,38)(27,34,33,39)(30,37,36,40)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.