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