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