I have found a solution.
For those looking to do the same, you can modify the rootrc file as mentioned in section 2.7 of: https://root.cern.ch/root/htmldoc/guides/users-guide/ROOTUsersGuide.html#the-root-command-line
Specifically, within the rootrc file, there are the variables:
#Rint.TypeColor: bold blue
#Rint.BracketColor: bold green
#Rint.BadBracketColor: bold red underlined
#Rint.PromptColor: default
#Rint.TabComColor: magenta
By un-commenting these lines and setting their values to default
, the REPL will keep the current terminal colour.