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