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