Finding Windows 10 drivers, or drivers in general, for the Surface 3 machine can be a bit challenging since Microsoft decided to change the search experience for their download site from poor to worse. Anyway, the trick is to Google/Bing for the Surface Pro 3 drivers which are available here: http://www.microsoft.com/en-us/download/details.aspx?id=38826
When you expand the Details node in the Surface Pro 3 drivers download, you see the links to Surface 3 drivers:
Surface 3: http://www.microsoft.com/en-us/download/details.aspx?id=49040
Surface 3 LTE ATT: http://www.microsoft.com/en-us/download/details.aspx?id=49039
Surface 3 LTE North America Carrier Unlocked: http://www.microsoft.com/en-us/download/details.aspx?id=49037
Surface 3 LTE Outside of North America and Y!mobile Japan: http://www.microsoft.com/en-us/download/details.aspx?id=49041
Expanding Details on Surface Pro 3 drivers will show you links to Surface 3 drivers.