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