It depends on what you mean by "really".
That image was made for Peter Jackson's movies, and has little basis in Tolkien's own writings. Tolkien himself never described Sauron, in either his "beautiful form" or his "evil form" in any great detail, so you're never going to get any definitive or canonical representation.
The most detail we have is the following from The Council of Elrond:
...in that time he was not yet evil to behold...
And from Of the Rings of Power and the Third Age:
...for long if he willed he could still appear noble and beautiful, so as to deceive all but the most wary.
And other similarly brief descriptions elsewhere.
Based on these, that image is as good an interpretation as any, but an interpretation is all it can ever be.
Having said all of that, it's also important to note that (before he lost the power to do so at the end of the Second Age) Sauron could freely change shape and appear however he wished to observers. This is initially expressed in the Valaquenta (in a passage specifically relating to the Valar, but which we may assume also applies to the Maiar):
Moreover their shape comes of their knowledge of the visible World, rather than of the World itself; and they need it not, save only as we use raiment, and yet we may be naked and suffer no loss of our being ..... But the shapes wherein the Great Ones array themselves are not at all times like to the shapes of the kings and queens of the Children of Ilúvatar; for at times they may clothe themselves in their own thought, made visible in forms of majesty and dread.
And we see an explicit example of him actually doing it in Of Beren and Lúthien:
Therefore he took upon himself the form of a werewolf, and made himself the mightiest that had yet walked the world; and he came forth to win the passage of the bridge.
So it's actually completely incorrect to even speak of 'Sauron in his original "Maiar" form' because this form doesn't even exist.