How to make data points in ggPredict plot more transparent?

this is my code:

fit4=lm(Response~r*delta*sw,data=ChemResearch4)
    summary(fit4)
b<-ggPredict(fit4,colorn=10,add.data=FALSE)+
plot(b)+
  labs(
    x = "r",
    y = "Response",
    title = "Effect of delta and r on response, by sw values")

This is the plot:

Thank you!

I tried geom_point, but it constantly shows error.

I don't see an option to change the transparency within the ggPredict function itself, but since it produces a ggplot object, you can add transparency as an aesthetic parameter to the point layer after the plot is produced.

We don't have your data, so here is a full reprex using the built-in mtcars data set:

library(ggiraphExtra)

fit4 <- lm(mpg ~ wt * hp, data = mtcars)

b <- ggPredict(fit4, colorn = 10, add.data = FALSE) 

plot(b)

Note the points are fully opaque. To make them transparent, we can do:

b$layers[[1]]$aes_params <- list(alpha = 0.2)

plot(b)

^{Created on 2023-07-13 with reprex v2.0.2}