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