This is easily achieved using the themes in ambiance-colors. (There is also a radiance-colors theme if you prefer the radiance theme.) To install:
sudo add-apt-repository ppa:ravefinity-project/ppa
sudo apt-get update
sudo apt-get install ambiance-colors
After this, use either Ubuntu Tweak or MyUnity or Gnome Tweak to change themes. You'll find in the list of themes - in all of those tools - a number of new ambiance themes, such as ambiance-blue, ambiance-red, etc. Make sure to change the theme both under "Window Theme" and under "GTK Theme."
The user in the picture has also installed an icon theme that uses blue folder icons, but I don't know which icon theme it is (although it might be HumanityBlue). There are a number of them, though. (If you search Google under "Ubuntu icon theme" you'll find quite a few. I use Faenza, but there are many others available.)