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