I do not have any information on a project called "Saudi Vellakka" or any individual named Manjusha Radhakrishnan associated with costume design for such a project. It's possible that this project or person gained prominence , or it might be a lesser-known work or individual.
To find information on how Manjusha Radhakrishnan designed costumes to reflect each character's personality in "Saudi Vellakka," you may need to conduct a more recent search on the internet or refer to the specific sources and publications related to the project. Websites, interviews, or articles related to the film or theater production might contain insights into the costume design process and its connection to the characters' personalities.
If "Saudi Vellakka" is a newly released work or a project that gained traction after 2023, I apologize for not having relevant information.