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