GLfloat intertwined[] = /* both vertex and color arrays in one */
{
1.0, 0.2, 1.0, 100.0, 100.0, 0.0,
1.0, 0.2, 0.2,   0.0, 200.0, 0.0,
1.0, 1.0, 0.2, 100.0, 300.0, 0.0,
0.2, 1.0, 0.2, 200.0, 300.0, 0.0,
0.2, 1.0, 1.0, 300.0, 200.0, 0.0,
0.2, 0.2, 1.0, 200.0, 100.0, 0.0
};

glColorPointer(3, GL_FLOAT, 6*sizeof(GLfloat), &intertwined[0]); /* refers to 1.0, 0.2, 0.2 */
glVertexPointer(3, GL_FLOAT, 6*sizeof(GLfloat), &intertwined[3]); /* refers to 0.0, 200.0, 0.0 */