Siri Vaheguru jee in Siri Guru Granth Sahib jee is always referred to as masculine and this is due to lack of any other way to address Him. In Sanskrit they have three genders and the third one being neither male nor female but in Punjabi or Hindi, there are only two genders. Our Guru Sahib have chosen to address Siri Vaheguru jee as "He" or "Him", so we should accept this Hukam. Even when Vaheguru jee is called "Mata", the Shabad says "Mera Mata" and not "Meri Mata" as one would say referring to one's mother.
Of course, Vaheguru Sahib jee does not have a gender in worldly sense but since our Guru Sahibaan have chosen to address Vaheguru jee as masculine, we should take cue from this and do the same.
Kulbir Singh