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