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