R code used to produce the graph shown below.

par(mar = c(0.5, 2, 3.5, 2)) 
headers <- c("gray", col.tint("blue", .5), col.tint("blue", .6), col.tint("blue", .7)) 
 
cellcol2 <- cbind(rep(c("gray", col.tint("gray", .5)), 3), 
                  rep("white", 6), 
                  as.vector(cellcol[1:2,2:4])) 
 
colnames(longdf) <- c("ID", "time", "value") 
 
 
color2D.matplot(longdf, 
                show.values = TRUE, 
                axes = FALSE, 
                xlab = "", 
                ylab = "", 
                vcex = 3, 
                vcol = "black", cellcolor=cellcol2) 
 
axis(3, at = seq_len(ncol(longdf)) - 0.5, 
     labels = names(longdf), tick = FALSE, cex.axis = 2.5)