Do you intend that when players A B & C are allocated a board that :
A plays B while C scores, then
A plays C while B scores, then
B plays C while A scores.
If you want this, then unfortunately it can not be made to work for 42 players, however 39 and 45 players are possible.
Alternatively, if it doesn't really matter who scores whom, then you just consider it as arranging a standard 42 player round robin in rounds of 14 games. I can make this I think.