I haven't looked at your code but controlling the colors of the plots is easy enough; you create a property node of the graph and select two properties; active plot and plot color...Write the index of the plot you want to set the color of to the active plot property and then the color you want to the color property. If you have multiple plots and want to color all of them in a row create an array of the colors you want to use, wire it to a for loop with the property node with the two properties inside...wire the loop index to the active plot and the autoindexed color to the color.
Now perhaps you want to automatically generate that array of colors? Check out e.g. this thread:
http://exchange.ni.com/servlet/ProcessRequest?RHIVEID=101&RPAGEID=135&HOID=50650
0000008000000B2350000&UCATEGORY_0=_49_%24_6_&UCATEGORY_S=0&USEARCHCONTEXT_QUESTION_0=color+array&USEARCHCONTEXT_QUESTION_S=0