Mentioning graduates names in the SOP?
I think it would be ok, if done in passing; less than a sentence, perhaps. I think it would be much better, however, if one of your letters of recommendation mentioned the earlier (successful) student instead. I once benefitted from just that situation.
But, a word of caution. Make sure that your SoP is forward looking on your own plans and goals and how you intend to meet them. Don't get side tracked from the fact that this is, perhaps, your most important application document. Having someone else say certain things gives you a few more words to make the most important points.