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