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