Definitely a female. Females have the speckles all the way down to the bottom half of the face like yours, while males only have them on the top half. Males sometimes have more vivid coloration in most cichlids but in dempseys the female can be quite colorful as well.
Another way I can tell is through the anal and dorsal fins in males they tend to have taller and longer fins sometimes extending past the tail. Lastly males are larger. If your fish is reaching near 10" its a male. Females will probably never grow past 7"
Also, are you keeping your fish over light sand? a darker substrate wil help to bring out her colors more