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