I try to represent point layer with different size and i want to have a color ramp also:

[![enter image description here][1]][1]

The problem is that when i  choose the color method, the size method disappear:

[![enter image description here][2]][2]  

I can change the color manually, but i seek for automatic way.

I also have red this https://gis.stackexchange.com/questions/148374/how-to-deactivate-the-color-ramp-in-qgis-graduated-vector-styling and didn't got my wanted answer. 


  [1]: https://i.sstatic.net/qT6UE.jpg
  [2]: https://i.sstatic.net/XNn9F.jpg