The minimalist look can be achieved by appending the
following chunk of code to the output object:
+
xlab(NULL) +
ylab(NULL) +
theme(
   axis.text = element_blank(),
   axis.ticks = element_blank(),
   legend.position = 'none',
   strip.background = element_blank(),
   plot.background = element_blank(),
   panel.background = element_blank(),
   panel.border = element_blank(),
   panel.grid = element_blank(),
   panel.border = element_blank()
)