Depends on the business, but most of the 40% is employer contributions to payroll tax, health insurance, and other per-employee costs, and the 20% overhead is "general and administrative" (office manager, professional services, coffee, etc), coverage for non-billable employees like sales folks (including otherwise billable employees who are below 70% due to winning you the gigs keeping you at ~70%), and what have you.

If it isn't obvious, this is a bit handwavy; particular jurisdictions will have rates/requirements which materially influence the 140% figure, etc.

140% fully loaded also sounds a bit low.

Not patio, but typically the 40% TCO includes items that scale ~linearly with the number of employees -- health insurance/other benefits, payroll taxes, etc. The 20% of overhead is for things like office space, business insurance, and to cover the salaries of employees like accountants and HR (who are essential but not billable to clients).

Not OP but heath insurance, taxes and other costs that can be marked down exactly as being for Employee #X are in the 40%.

Paying for an office having light, power, internet, management, and a mailroom is in the 20%.