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