I can see number of permission sets created in the org through SOQL. but Could not see because of Insufficient Privileges Errors. please suggest how can I see?
To Manage permission sets, you need following user permissions. "Manage Profiles and Permission Sets". You can go to your profile and edit this permission or you can ask your System Administrator to do this.
Also check the list view by click on edit and see if it is filtering anything.
You may not see each and every permission set in the UI as some permission sets belong to a profile. You can filter them via
IsOwnedByProfile field on PermissionSet Object. The permission sets where this field is true will not show up. Link