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