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