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