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