Use this if you are using igraph from R
| sequential_pal {igraph} | R Documentation | 
This is the ‘OrRd’ palette from https://colorbrewer2.org/. It has at most nine colors.
sequential_pal(n)
| n | The number of colors in the palette. The maximum is nine currently. | 
Use this palette, if vertex colors mark some ordinal quantity, e.g. some centrality measure, or some ordinal vertex covariate, like the age of people, or their seniority level.
A character vector of RGB color codes.
Other palettes: 
categorical_pal(),
diverging_pal(),
r_pal()
## Not run: 
library(igraphdata)
data(karate)
karate <- karate %>%
  add_layout_(with_kk()) %>%
  set_vertex_attr("size", value = 10)
V(karate)$color <- scales::dscale(degree(karate) %>% cut(5), sequential_pal)
plot(karate)
## End(Not run)