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