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