transparent colors in ggplot2

library(tidyverse)
library(wesanderson)
mean_steps <-  read.csv("data.csv", stringsAsFactors = FALSE)

cols = c("#FF0000", "#00A08A", "#F2AD00")
cols2 = paste0(cols, "80") 
cols = c(rbind(cols2, cols))

ggplot(data=mean_steps,aes(x = trial, y = mean_same, color = paste(block, actor))) +
  stat_summary(fun="mean",position=position_dodge(width=0.1), 
               geom="line" ,size=2) +
  geom_hline(yintercept = 50,linetype="dashed", color = "grey",size=1)+
  scale_y_continuous(name="Percentage correct chosen (%)", breaks = seq(0, 100, 25)) +
  scale_x_continuous(name="Trial", breaks = seq(0, 20, 4)) +
  facet_wrap(.~block, strip.position="top")+
  scale_color_manual(values=cols) +
  theme(
    legend.title = element_blank(),
    axis.title.x = element_text(size = 10, vjust = -0.35),
    axis.title.y = element_text(size = 10, vjust = 0.5),
    axis.text.x = element_text(size = 8, vjust = 0.5),
    axis.text.y = element_text(size = 8, vjust = 0.5)
  )