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