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