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