How Do I Add Color to My Convex Hulls

I've created convex hulls for an NMDS plot but I don't know how to change their colors. How would I go about this?

#codes
phylum.dat <- read.csv("Phylum data for R.csv", stringsAsFactors = T, header = T, row.names = 1)
diversity(phylum.dat, index = "shannon")
specnumber(phylum.dat) #species number
beta <- vegdist(phylum.dat, "jaccard", binary = TRUE) #jaccard distance
mean(beta)
dist(beta) #distance matrix
NMDS <- metaMDS(beta, distance = "jaccard", k = 2)
plot(NMDS, display = "sites", type = "text") #adds labels to plot
treat=c(rep("Treatment1",4),rep("Treatment2",4),rep("Treatment3",4))
ordihull(NMDS,groups=treat,draw="polygon",col="grey90",label=F)

image

ordihull(NMDS,groups=treat,draw="polygon",col= c("red", "blue", "green"), label=F)