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