De Graag's artistic style was characterized by her bold use of color, expressive brushwork, and a unique blend of realism and abstraction. She was known for her ability to capture the essence of her subjects, whether it be landscapes, still life, or portraits, with a sense of emotion and vitality.

Her technique involved using loose brushstrokes and vibrant colors to create dynamic and atmospheric compositions. De Graag often experimented with different mediums, including oil, watercolor, and pastel, allowing her to explore the versatility of each medium and push the boundaries of traditional art forms.

Throughout her career, De Graag explored a wide range of themes and subjects in her artwork. She had a particular affinity for landscapes, capturing the beauty of the Dutch countryside with a sense of reverence and tranquility. Her landscapes often featured sweeping vistas, vibrant colors, and a sense of movement, evoking a feeling of connection with nature.