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