Custom color scheme for ggplot

color_scheme.r

c.blue   <- "#0072B2"
c.yellow <- "#E69F00"
c.green  <- "#009E73"
c.red    <- "#D55E00"
c.pink   <- "#CC79A7"
c.gray   <- "#999999"

palette <-  c(
  'follow'=c.blue,
  'newuser'=c.yellow,
  'post'=c.green,
  'repost'=c.red,
  'timeline'=c.pink,
)

color_scales <- function(title, palette)
  list(
    scale_fill_manual(values=palette, name=title),
    scale_color_manual(values=palette, name=title)
  )

ggplot(...)+color_scales(title='Transaction Type')

(where follow, newuser, etc are levels in a factor you wish to color)