You do not fully state what your problem is. Can it be assumed that there are seven imput variable lines (the six "S" lines, and the enable M)? If so, then there are 2^7, or 128 possible input line combinations. That makes for a long truth table, but it isn't difficult to work with. There are two basic approaches to working with this. 1) Either you can put everything into a 128 combination truth table, or 2) for each desired output line, you can eliminate all inputs that don't pertain to it, and then make four truth tables, one for each of those desired outputs.
First, though you need to specify clearly what the inputs mean, and from this what input combination drives each of the outputs.