Hi @enzo,
Thanks for the code. We have in fact implemented a customisable biplot function which is still in development 
.
Below is an example with installation instructions:
BiocManager::install('ajabadi/mixOmics@devel', ask=FALSE, update = FALSE)
library(mixOmics)
data(breast.tumors)
X <- breast.tumors$gene.exp
colnames(X) <- paste0('GENE_', colnames(X))
rownames(X) <- paste0('SAMPLE_', rownames(X))
Y <- breast.tumors$sample$treatment
plsda.breast <- plsda(X, Y, ncomp = 2)
biplot(plsda.breast, cutoff = 0.72)
## remove arrows
biplot(plsda.breast, cutoff = 0.72, var.arrow.col = NULL, var.names.size = 4)
Created on 2020-10-27 by the reprex package (v0.3.0)
You can see more examples a ?mixOmics::biplot. Iād appreciate your feedback on what I could further improve .
Hope it helps,
Al