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