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