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