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