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