The word vocation and catechist are not always used together. However, the article cited below explains how serving as a catechist (religious education teacher) is a "calling." It follows the understanding of Pope Francis who recently elevated the role of catechist as a ministry in the Church.
Article by Joe Paprocki, Loyola Press webpage
Recruiting and forming catechists is a primary responsibility for catechetical leaders and is an ongoing challenge. You’re not just looking for any warm body but for people with the gifts that enable them to apprentice others into the faith.