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