This study investigates the use of design elements in the advertisement posters on the Facebook pages of ten Thai universities, comprised of five government and five private institutions. Using the Multimodal Corpus Analysis Tool (MCAT), the study systematically analyzed the color characteristics and dominant colors employed in the universities' Facebook advertisement posters. Findings revealed that while color characteristics were similarly employed across the universities, the use of dominant colors varied significantly. Government universities were found to incorporate their theme colors in the designs, reflecting their brand identity. In contrast, private universities predominantly used colors to augment the content of their advertisements, rather than to represent their institutional identities. This study provides valuable insights into how different color and design elements are utilized by Thai universities in their social media communication to enhance their brand identities and content messaging.