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