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