I notice GSEA automatically geneartes a heat-map like diagram for the pathways but does not include a 'scale' bar. 
I tried to get a better understand on how the heat map is plotted, but the explanation is not very clear on the tutorial site. 
Does anyone know how is the heat map generated? Are the colors based on fold change, or something else?

Thank you 

Hi! My understanding is that expression levels are visualized by colors, with high expression shown in red and low expression shown in blue:
"In a heat map, expression values are represented as colors, where the range of colors (red, pink, light blue, dark blue) shows the range of expression values (high, moderate, low, lowest)."