Enable sudo without a password

edit /etc/sudoers

sudo visudo

Then find the admin group permission section:

%admin          ALL = (ALL) ALL

%wheel  ALL=(ALL)       ALL

Change to add NOPASSWD:

%admin          ALL = (ALL) NOPASSWD: ALL

user    ALL=(ALL)       NOPASSWD: ALL

Be aware that removing the password requirement to use sudo eliminates a level of security. If someone gains access to your account they will be able to easily escalate to root privileges.