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