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