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