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