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