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