If a change in semen color is unusual or sudden, you should talk to your doctor.
Semen is normally a whitish-gray color.
Living with Lupus:
Leukocytospermia happens when too many white blood cells leukocytes are present in your semen.
Lifestyle factors, such as smoking and drinking, can cause a change in the colour of your semen.
Weiss BD, et al.
Although the exact reason unknown, it something to do with a seminal vesicle malfunction.
Sperm is secreted by the testicles, travels through the epididymis to the vas deferens and then combines with fluids from the seminal vesicles, the prostate, and the bulbourethral and urethral glands before leaving the body.