  The evidence of a new scalar particle $X$ from the 750 GeV diphoton excess,
and the absence of any other signal of new physics at the LHC so far suggest
the existence of new colored scalars, which may be moderately light and thus
can induce sizable $X g g$ and $X \gamma \gamma$ couplings without resorting to
very strong interactions. Motivated by this speculation, we extend the
Manohar-Wise model by adding one gauge singlet scalar field. The resulting
theory then predicts one singlet dominated scalar $\phi$ as well as three kinds
of color-octet scalars, which can mediate through loops the $\phi gg$ and $\phi
\gamma \gamma$ interactions. After fitting the model to the diphoton data at
the LHC, we find that in reasonable parameter regions the excess can be
explained at $1\sigma$ level by the process $ g g \to \phi \to \gamma \gamma$,
and the best points predict the central value of the excess rate with
$\chi_{min}^2=2.32$, which corresponds to a $p$-value of $0.68$. We also
consider the constraints from various LHC Run I signals, and we conclude that,
although these constraints are powerful in excluding the parameter space of the
model, the best points are still experimentally allowed.
