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