I have encountered an issue in JMP when plotting multiple levels of information in one plot.
For example, the colour in the top graph is defined by age, while the colour in the bottom graph is defined by sex.
By default, JMP uses the same marker type for all plots.
This makes it difficult for the human eye to interpret the information in the legend and in the plot ('Is the purple dot 15 or F?'); even the human brain needs time to process the information.
"I am in the upper plot - with ages. I can ignore the F & M and focus on the numbers in the legend. Purple corresponds to "age=15".

you can use this script to optimize the plot on your own:
dt = Open( "$SAMPLE_DATA/Big Class.jmp" );
Graph Builder(
Size( 485, 480 ),
Summary Statistic( "Median" ),
Graph Spacing( 4 ),
Variables(
X( :height ),
Y( :weight ),
Y( :weight ),
Color( :age ),
Color( :sex )
),
Elements( Position( 1, 1 ), Points( X, Y, Color( 1 ) ) ),
Elements( Position( 1, 2 ), Points( X, Y, Color( 2 ) ) )
);
NB:
This example was chosen to highlight the problem.
Clearly, for this example, more meaningful settings would be to have just one plot and sex = marker | age= color
... which is not possible for the real, more complex application case.