How to draw a multivariate linear regression graph with multiple lines based on selected variable

[#1]

I wan to draw a graph like the first pic, but when I have 3 variables in a new model, my graph looked like the second one. How do I draw multiple lines?

[#2]

Currently, I guess you probably have a category column in the "Color" role, to give your datapoints three different colors. But they are still treated as the same dataset, so only one trend line is shown. 

Instead of using the "Color" role, drag that category variable to the "Overlay" role. That should give three sets of points, and three trend lines. 

More info: Graph Zones 

[#3]

Hey, so there is a lot to guess about in this question.

What platform are you using?  Fit Y by X?

look for this option