R tm package - control weights and edge colors

I am trying to plot a plot with weighted and colored edges using the tm package in R. The problem is that the correlations are pretty strong, so the edge widths cover most of my plot. I can control the fact that they are weighted, although they don't have time to color them light gray, so it won't cover the rest of the graph. My code:

plot(dtm,terms = findFreqTerms(dtm, lowfreq=400),corThreshold = 0.3,weighting = TRUE,attrs = list(graph = list(rankdir ="BT"),node = list(shape = "rectangle",fixedsize=FALSE,fontsize=120)))

      

        
        
        
      

    

which works great except for very wide and dark edges.

An alternative solution I was thinking about is converting an object to a graph object, but with no success.

Any help would be much appreciated. Many thanks.