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