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)(11,14)(12,16)(13,21)(15,18)(17,23)(19,24)(20,22)(25,26,30,33)(27,31,34,28)(29,32,38,40)(35,39,37,36)(2,5)(6,7)(9,10)(11,14)(12,16)(13,17)(15,18)(19,22)(20,24)(21,23)(27,34)(28,31)(35,37)(36,39) involution — undirected(1,2)(3,6)(4,5)(7,8)(9,11,15,12)(10,16,18,14)(13,19,23,20)(17,24,21,22)(25,27)(26,31)(28,33)(29,37)(30,34)(32,36)(35,38)(39,40)(1,3)(2,6)(4,8)(5,7)(9,12,15,11)(10,16,18,14)(13,20,23,19)(17,24,21,22)(25,28,30,31)(26,27,33,34)(29,36,38,39)(32,35,40,37)(9,13,15,23)(10,17,18,21)(11,19,12,20)(14,22,16,24)(9,14,15,16)(10,11,18,12)(13,22,23,24)(17,19,21,20)(25,29,30,38)(26,32,33,40)(27,35,34,37)(28,36,31,39)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.