What you can do is use 3 MAC7219 per matrix, as long as the matrix are common cathode RGBs, and take advantage of their Shutdown mode:
"When the MAX7219 is in shutdown mode, the scan oscillatoris halted, all segment current sources are pulled to
ground, and all digit drivers are pulled to V+, thereby blanking the display."
You will need to add 8 schottky diodes (~0.3V drop) per MAX7219 on the DIGIT pins, which control the common cathode.
On each Digit pin, connect the diode anode to the common cathode of the matrix, and the diode cathode to the MAX7219, so the active MAX7219 can pull the common cathode low to enable the column being driven (MAX7219 muxes the matrix at 800 Hz, so you can't really do more than turn each one off or on).
Multiplex each color in software by having 2 MAX7219's in shutdown while the 3rd is active so that only 1 color at a time is being driven.
If each color is left on for 5mS at a time, that would yield a 15mS refresh time or 67 Hz. Could try 10mS per color, 33 Hz, see how that looks.
Be sure to use SPI.transfer( ) to send the data and shutdown commands out so the changes are made quickly.