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