An employer may choose to include this benefit on an employee’s Form W-2 (under Box 14, for “Other”); but this is entirely optional.
Instructions to Form W-2 states that filers may use Box 14 for information that they would like to provide to their employees. An employer can choose to report Code §132(f)(4) deductions on Form W-2 (under Box 14, for "Other"), but this is entirely optional.
Per IRS Publication 15 b: Generally, you can exclude qualified transportation fringe benefits from an employee's wages even if you provide them in place of pay. For information about providing qualified transportation fringe benefits under a compensation reduction agreement, see Regulations section 1.132-9(b)(Q&A 11–15).