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