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