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