It is mustahab to lift ones hand when making dua at the graveyard.(Ahsanul Fatawa Vol.4 Pg.234)
The sunnat manner would be to stand facing qibla and lift ones hands in dua, however to make dua any other way would also be permissible. One should however not adopt any such posture that could give onlookers the impression that one is worshipping the grave or asking his needs from the inmate of the grave. (Fataawa Rahimiyyah Vol.7 pg. 89-Darul Ishaat)
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai