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