This is obviously a pretty rough and ready guide. For starters because we've used different formations over the years and the positions aren't always clear-cut, and also because players get shifted around the place, and sometimes spend ages covering what is not their "natural" position. Still thought it'd be useful to make some sort of an attempt at it.

Goalkeeper
Right-back
Left-back
Central defender
Winger
Midfielder
Striker

Captains