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