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