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