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