A bit of a loaded question, that... Can you link to a photo, or post one for us?
A captive bred young turtle might show color earlier in life due to (probably) being fed year round. A 4 yr. old CB turtle that was raised that way would probably be near-adult size and should show some color. Sometimes, though, CB turtles can have a somewhat dull coloration as a result of poor diet and husbandry.
A wild young turtle, or one that has been allowed to hibernate each winter, will be somewhat smaller and MAY not show as much color, although wild or semi-wild youngsters I have seen have been, in some respects, more colorful, earlier, that CB's.
Or the turtle in question may just not have much of a pattern, or may not be an Eastern at all, or may be an Eastern crossed with, say, a Three Toed and not have much of a pattern as a result.
Lots of variables.