If you look at the instructions available at: https://medicine.careers360.com/articles/neet-admit-card it no were mentions that the admit card should be a coloured print. It is only easy for identification and easy security check why a coloured print is advised. You do not want last minutes hassles during security check. So try to take a coloured print out of the admit card and make sure you keep 3-4 copies aside for future reference.

NTA has released advisory for Students:

• Free masks wil be made available at the exam centers
• Students and Invigilators will be checked for temperature at the entry point
• To minimise the risk of the virus, there will be separate isolation rooms for Candidates showing the symptoms or those having above normal body temperature
• Regarding the self declaration form, It says that you do not have any COVID-19 symptoms and have not come in contact with anybody who has symptoms or has been tested positive in the recent past. You have to sign this form in the presence of the Invigilators. You will have to fill this form and sign it.
• The admit card is a 3 page pdf. Page 1 will have Exam centre details and self declaration form. Page 2 will  have Important exam Instructions to the Candidates. Page 3 will have Advisory for Candidates.
• Candidates will be given staggered reporting slots
• Candidates will be seated within a distance of 6 ft

Hi student,

Yes, you can go for black and white admit card printout as they are also allowed in the examination hall for JEE and NEET Exam. But in instructions it is written that colour printout should be there. So, to be on the safer side I would suggest you to take colour printout only.

Refer here for more info - https://engineering.careers360.com/articles/jee-main-admit-card

Feel free to ask doubts in the Comment Section.

I hope this information helps you.

Good Luck!