There is in JMP a default color, green, which is used in many graphs (for example in the histogram made in the graph builder). This color could be changed for any particular graph, but you have to do this for each one of them, which can be painful. Following a post in the forum, an expert user suggest a JSL script:
Preferences( Histogram Color( "LightBlue" ) );
which works. So the suggestion is simply to add a preference for this color in JMP preferences windows.