When editing an ordered sketch, this command displays the color for an element based on the degrees of freedom for the element. For example, an element that is fully constrained displays in a different color than an element that is not fully constrained. This allows you to determine if the profile or sketch needs more relationships applied.
You can use the Colors tab on the Options dialog box to set the colors you want to use.
Note:
When you set the Sketch Relationship Colors option, the Line Color button on all create or edit 2D element and Select Tool command bars is not available and you cannot apply or change element colors.