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