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