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