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