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