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