The latest Os Nougat 7.0 came with latest Google Keyboard Theme version which has 15 set themes of all the beautiful colors in the world. Ranging from girlish pink to icy blue, the Google Keyboard themes looks amazingly beautiful with the material design configuration feel of Android. You can change the theme to your taste if the present one is enough, you can even set an image of your own as the keyboard background. All of it looks absolutely beautiful.
To get Google Keyboard themes, install/update the Google Keyboard app on your device from the Play Store. Link here
We should know that Android 7.0 Nougat features a slightly different keyboard settings layout,