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