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