Comparing graph of stratified cox model to others in R

Question

I\'m looking at the bfeed dataset in R:

dput(head(bfeed))
structure(list(duration = c(16L, 1L, 4L, 3L, 36L, 36L), delta = c(1L, 
1L, 0L, 1L, 1L, 1L), race = c