Probably exactly as it would look to a Muggle standing in front of it
There is no canonical information available for how Hogwarts (or any other Unplottable wizarding location) would appear on satellite images. However, this would make the most sense.
Satellite images are basically just pictures. We know that the wizarding world knows about, and even uses, cameras. Therefore, they would have likely made sure that the enchantments used to hide Unplottable areas from Muggles would also work to keep magical locations appearing the way would look to a Muggle standing in front of it in Muggle pictures as well. It would raise suspicion if a Muggle happened to take a picture of what they thought was a castle ruin or something similarly unremarkable, and later saw they had taken a picture of something else.
Presuming that spells to change the way a location looks to Muggles work somewhat like the Invisibility Cloak, hiding the location itself rather than working on the device taking the pictures, the satellites being far away should have no effect on the magic used to conceal their true appearance. If this is the case, wizards would not even need to be aware of the existence of satellite technology to keep wizarding places hidden from it. It would be done automatically by the protective spells already in place to prevent Muggle pictures of magical locations.