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