You can talk about your soft skills throughout the whole application process.

In the Resume:

Use numbers to illustrate the impact you have made. For example, provide the number of people you have trained / mentored, the size of the team you’ve worked with, or the audience size to which you’ve given a presentation.

In the Cover Letter:

Tell short stories that highlight the use of soft skills. You can reiterate the numbers from your resume in depth, but make sure to mention any mentorship, teaching or teamwork experiences, or when you’ve engaged with customers in a meaningful way. 

In the Interview:

Include soft skills in your answers. As you tell your story using the STAR method, provide examples of how your soft skills helped you solve a problem or manage a complication situation. When a “how did you…” question is asked, you can generally include your soft skills within your answer.