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