A Corporate jet pilot reported they taxied onto a closed taxiway at MEI due to insufficient closed taxiway markings and lack of signage.

Narrative

We landed on Runway 19 at MEI and during the left turn off the runway the Tower instructed us to exit at [Taxiway] Alpha 3 and left on [Taxiway] Bravo. We were abeam or past the taxiway sign for [Taxiway] Bravo so we continued straight ahead to the old now closed Taxiway Bravo. The Tower instructed us to stop and do a U-turn to the new [Taxiway] Bravo. We were not the first crew to have done this as I could see recent tire tracks and a broken taxi light on the old [Taxiway] Bravo. I have two suggestions. First; on the taxi chart we reviewed prior to landing the XXXX on the closed taxiway are faint. They do not stand out. They in fact are considerably less distinct than the oddly depicted airport perimeter fence or road. Why is the perimeter fence/ road on the chart? My second suggestion is wouldn't a sign or clear barricade prohibiting entry onto the old [Taxiway] Bravo be better. There is a yellow X on the ground but by the time you see it you are already on the taxiway with not much of a option to turn around. Lastly the entire issue could have been avoided if the Tower had said; exit at [Taxiway] Alpha 3 and make the 'FIRST' left onto [Taxiway] Bravo. That one additional word would have saved us all.