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