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