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