The schematic (at E30) shows that wire goes two places. A rollover switch on the playfield, and impulse switch D. So it just goes back into the wiring harness, not to something nearby, so it's just been cut randomly there. There's a loop of the same color wire below it in the picture, is there the other cut end on one end of that loop?
M 30 1400 is a coil PART number, not a number identifying which coil it is in the game. M is the bobbin type, 30 is the wire gauge, 1400 is the number of turns.