No, the sign of the gap does not represent particle-hole symmetry. The superconducting gap simply being non-zero automatically encodes the existence of particle-hole symmetry. Variations in the sign of the gap in the Brillouin zone (BZ) determines whether a superconductor is topologically trivial or non-trivial. However, topological or not, a superconductor will possess particle-hole symmetry.
I believe some background information might provide some context to the general readers. For a time-reversal invariant 3D topological superconductor the topological invariant or winding number can be written as $$N_{W}=\frac{1}{2}\sum_{s}{\rm sgn}(\delta_{s})C_{s}$$ where $$C_{s}=\frac{1}{2\pi}\int_{{\rm FS}_{s}}d\Omega^{ij}\left[\partial_{i}a_{sj}({\bf k})-\partial_{j}a_{si}({\bf k})\right]$$ is a Chern-number-like quantity evaluated over the $s^{{\rm th}}$ Fermi surface (which is 2D for a 3D superconductor), $a_{si}=-{\rm i}\left\langle s{\bf k}\right|\partial/\partial k_{i}\left|s{\bf k}\right\rangle$, where $\left|s{\bf k}\right\rangle$ is a Bloch state on the $s^{\rm th}$ Fermi surface, ${\rm sgn}(\delta_{s})$ represents the sign of the gap on the $s^{{\rm th}}$ Fermi surface, and $i,j=x,y,z$. The $s$ different Fermi surfaces also need to be disconnected in the BZ. Corresponding expressions can be found in lower dimensions by a formal procedure called “dimensional reduction.” However, let’s focus on the 3D case for now.
If our system obeys time-reversal symmetry then $$\sum_{s}C_{s}=0$$ For a conventional $s$-wave superconductor, the sign, by definition, is constant throughout the BZ. This always implies $N_{W}=0$ in a time-reversal invariant system. For example, for a system with 2 disconnected Fermi surfaces, (say) we have $C_{\pm}=\pm 1$. For an $s$-wave superconductor ${\rm sgn}(\delta_{\pm})=+1$ (or $-1$ for both). Then we obviously have $$N_{W}=\frac{1}{2}(+1)(+1)+\frac{1}{2}(+1)(-1)=0$$ But if ${\rm sgn}(\delta_{\pm})=\pm 1$ (say fully gapped $p$-wave), then $$N_{W}=\frac{1}{2}(+1)(+1)+\frac{1}{2}(-1)(-1)=1$$ In summary, both cases have particle-hole symmetry. The sign of the gap simply indicates topological character.
Further details regarding the above formalism can be found in
Xiao-Liang Qi, Taylor L. Hughes, and Shou-Cheng Zhang. “Topological invariants for the Fermi surface of a time-reversal-invariant superconductor.” Physical Review B 81, no. 13 (2010): 134508. (arXiv)
