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