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