Serigraphy was the technique which Cajiga dedicated more time. His beginning task was to prepare and print mostly the works of Homar and Tufiño, artists whom Cajiga received more support and education. Working with the posters of these renowned masters of the graphics, our painter learned all referent to the serigraph, technique which he had been working for the past fifty years. He also learned drawing, water color, oil and engraving. He worked in some of the publications of the Division, including posters, drawings on books, and titles for movies.
The first poster of Cajiga was the one that he did for the Fire Department, which receive the second price in the contest that was convoked by Raúl Gándara, the legendary director of that department. He also realized some serigraphs, been the firs the "Escalerilla de las Monjas", in 1957. The first oil he painted is in the Santa Catalina palace (governor’s house) and the second is in Ponce Museum of Art. This piece, "Calle Mercado", was bought by the distinguished Luis A. Ferré, former governor of Puerto Rico.
Besides painting the streets of Old San Juan, Cajiga is renowned by his serigraphs and acrylics of scenes of Puerto Rican towns, suburbs, slums, and, over all, landscapes with flamboyant. He also painted portraits and religious themes like the Book of Revelations.