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