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