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