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