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