Your net gains in Euros can be calculated by working out what you would make from selling the stock (in USD) and converting to EUR:
current-EUR-value = current-USD-price x number-of-shares x USD-to-EUR-rate
and then deducting the initial purchase price in EUR:
current-EUR-gain = current-EUR-value - original-EUR-price
In your case, assuming you originally bought about 1,390 units (using an average EUR-to-USD rate from 2011 of 1.39), and a current (as at 16 November 2018) USD-to-EUR rate of 0.88, then:
current-EUR-value = $40 x 1,390 x 0.88 = 48,928€
current-EUR-gain = 48,928€ - 10,000€ = 38,928€
Therefore, your profit if you sold today (ignoring any commissions and dividned) would be 38,982€.
From clarification in comments, you could make a "what if?" conversion back at the old exchange rate: use 1/1.39 (~=0.72) for the USD-to-EUR-rate. This would give a figure of 40,000€ for what the shares would have been worth if the 2011 rate had stayed the same. Under this assumption, the "profit" would have been 30,000€ which is worse than the "real" figure.
However, this calculation is somewhat meaningless, as the rate has changed. Indeed, the change in relative strengths of the two currencies might be one factor in why the price of the stock has risen as much as it has.