Patterned Canvas

How do I change the colors of the patterns in the materials?

Arnold

1. In the material editor, select Open network editor:
2. Select any of the color nodes plugged in to the pattern layer and modify the color: 

Octane

1. In the material editor, click 'Node Editor'. (If you don't see it, check the basic tab.)
   
2. Select any of the color nodes and modify them:

Redshift

1. In the material editor, click Edit Shader Graph:
2. Select any of the RS Color Abs nodes plugged into the RS Color Layer and modify them: