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